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Search: id:A096507
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| A096507 |
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Numbers n such that 6*R_n + 1 is a prime, where R_n = 11...1 is the repunit (A002275) of length n. |
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+0
10
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| 1, 2, 6, 8, 9, 11, 20, 23, 41, 63, 66, 119, 122, 149, 252, 284, 305, 592, 746, 875, 1204, 1364, 2240, 2403, 5106, 5776, 5813, 12456, 14235
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OFFSET
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1,2
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COMMENT
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Also numbers n such that (2*10^n+1)/3 is prime.
No others less than 25557. These numbers form a near-repdigit sequence (6)w7.
All the terms from n = 2403 through 14235 correspond to primes. Joao da Silva (zxawyh66(AT)yahoo.com), Oct 3 2005
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LINKS
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Makoto Kamada, Factorizations of 66...667.
Index entries for primes involving repunits
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EXAMPLE
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n = 9 gives 2000000001/3 = 666666667, which is prime.
n=20 means that 66666666666666666667 is a prime number.
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CROSSREFS
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Equals A056657 + 1.
Cf. A096503, A096504, A096505, A096506, A096507, A096508.
Sequence in context: A047397 A043341 A023714 this_sequence A050675 A034591 A047278
Adjacent sequences: A096504 A096505 A096506 this_sequence A096508 A096509 A096510
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KEYWORD
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base,nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jul 12 2004
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EXTENSIONS
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More terms from Julien Peter Benney (jpbenney(AT)ftml.net), Sep 14 2004
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